Secure Sounding Signal Adaptation for Bandwidth Variation
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Solution Overview
Problem
Current 802.11az systems face challenges in adapting secure sounding signals to bandwidth variations, particularly in multiuser modes where phase and frequency offsets cannot be tracked due to unknown sounding signals, and lack pilot signals in secure ranging mode, affecting channel estimation and accuracy.
Innovation Solution
The proposed solution involves truncating the random HE-LTF sequence and CSD value to adapt to smaller bandwidths, incorporating phase shift feedback for efficient feedback type negotiation, and modifying pilot signals to be known to all STAs for tracking phase and frequency offsets, ensuring accurate channel estimation and secure communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secure sounding signals are used in multiuser modes, then communication security is improved, but phase and frequency offsets cannot be tracked due to unknown sounding signals
Solution Approach 1:
The sounding signal is segmented into two parts: a known pilot signal portion and a secure random HE-LTF sequence portion. The pilot signal is transmitted separately and is known to all STAs, enabling phase and frequency offset tracking, while the random HE-LTF sequence maintains security. This segmentation resolves the contradiction by allowing both security and offset tracking to coexist.
Solution Approach 2:
A known pilot signal acts as an intermediary between the secure random HE-LTF sequence and the channel estimation process. The pilot signal provides a reference that enables receivers to track phase and frequency offsets without revealing the secure random sequence, thus mediating between security requirements and measurement precision needs.
2Adaptability or versatility
If random HE-LTF sequence is truncated for smaller bandwidths, then bandwidth adaptability is improved, but implementation complexity increases
Solution Approach 1:
The system dynamically adapts the length of the random HE-LTF sequence based on the available bandwidth. For smaller bandwidths, the sequence is truncated to match the reduced number of subcarriers, while for larger bandwidths, the full sequence is used. This dynamic adaptation improves bandwidth versatility without requiring completely different signal designs for each bandwidth scenario.
Solution Approach 2:
The patent changes the parameter of sequence length based on bandwidth conditions. By adjusting the number of elements in the random HE-LTF sequence according to the available spectral resources, the system achieves bandwidth adaptability. The truncation process involves simple parameter adjustment rather than complex signal regeneration, managing implementation complexity.
3Measurement precision
If pilot signals are made known to all STAs for offset tracking, then channel estimation accuracy is improved, but security may be compromised
Solution Approach 1:
The sounding signal structure is segmented into a public pilot component and a private secure component. The pilot signal is designed to be known to all STAs and is specifically optimized for channel estimation and offset tracking, while the random HE-LTF sequence remains secret and is used for secure communication. This functional segmentation allows each component to optimize its specific purpose without compromising the other.
Solution Approach 2:
The pilot signal functionality is extracted from the secure random HE-LTF sequence and implemented as a separate, dedicated component. By taking out the channel estimation and offset tracking function into a separate known pilot signal, the patent enables accurate measurement while preserving the security properties of the random sequence that is not revealed to potential eavesdroppers.
Data Source
AI summary
This disclosure describes systems, methods, and devices related to adaptation of secure sounding signal. A device may determine a negotiated bandwidth to be used when communicating with a first station device. The device may determine a first bit stream used to generate a cyclic shift diversity (CSD) value based on the negotiated bandwidth, wherein a first number of bits is used for the first bit stream when a first negotiated bandwidth is used, and wherein a second number of bits is used for the first bit stream when a second negotiated bandwidth is used. The device may determine a second bit stream used to generate a random phase. The device may determine a secure a long training field (LTF) based on a combination of the first bit stream and the second bit stream. The device may cause to send a frame to the first station device, wherein the frame comprises the secure LTF.